Ajax said on Tuesday that Netherlands international Blind underwent a series of examinations following the incident that forced his substitution in the 1-0 win at the Johan Cruijff ArenA on August 25 and has been deemed fit to return.
The former Manchester United player was fitted with a subcutaneous implantable cardioverter defibrillator – a device that monitors and regulates his heart rhythm – after being diagnosed with heart muscle inflammation following a Champions League game with Valencia last December.
An Ajax statement read: "Daley Blind is training again with the Ajax first team. In a friendly match against Hertha Berlin on Tuesday, August 25th, the defender had to be substituted.
"Afterwards, Blind underwent a series of examinations which meant he was also unavailable for the Dutch national team.
"The results of the examinations concluded that there was no reason for Blind to stay on the sidelines any longer.
"Last week, the second captain began training in phases and this week he returned to full training."
Ajax is scheduled to begin its 2020-2021 Eredivisie campaign away to Sparta Rotterdam on Monday (AEST).